Demand is increasing in recent years for liquid crystal and electroluminescence (EL) display devices which have a large display area. A similar trend is found in the manufacture of these devices where multiple display devices are collectively fabricated from a single large-area substrate to reduce cost.
In addition, consumers like high quality display devices capable of producing a display that exhibits superior color uniformity with no dark spots or excess brightness (white) dots which are caused by defective display pixels.
It is however technically impossible, for example, to fabricate all defect-free pixels across the LCD color filter (CF) substrate or the EL substrate. It is also extremely difficult to manufacture display devices which have zero dark spots or excess brightness dots.
A known approach to these issues is to manufacture and inspect a large-area CF or EL substrate by conventional technology wherein defective pixels are subsequently reworked by dropwise dispensing of correction liquid by inkjet technology. See, for example, patent literature 1. The technology serves to produce large-area CF and EL substrates with no defective pixels and thus to produce high quality display devices.
Another approach employs inkjet technology not only for the reworking of defective pixels, but for the manufacture of the CF/EL substrate. Inkjet is also used to rework defects which occur during the manufacture. The technology is implementable by a single device which, to manufacture a defect-free substrate, incorporates a wide-array inkjet printhead capable of dispensing liquid drops across the substrate, a mechanism for detecting defective pixels from the dropwise dispensing by the wide-array inkjet printhead, and an inkjet printhead for reworking pixels which have been determined to be defective. See, for example, patent literature 2.
The reworking device described in patent literature 1 includes a defect detector, a laser projector, and an inkjet-based defect reworking unit. The device is capable of reworking defects on the substrate.
Patent literature 2 employs a supplementary inkjet device for reworking defects attributable to improper ejection by the wide-array inkjet printhead, so that a single device can produce a defect-free substrate. Meanwhile, there is strong demand for a high speed reworking process to further push the recent cost-cutting trend in display device manufacturing.